Rubber-reinforced thermoplastic resin compositions represented by ABS resins have well-balanced impact resistance, mechanical properties and shaping processability, and such thermoplastic resin compositions are widely used in various fields such as office automation equipment, automobiles and sundry goods. However, ABS resins are amorphous resins and thus have a large friction coefficient (dynamic friction coefficient, amplitude of dynamic friction coefficient) compared to crystalline resins such as polyethylene, polypropylene and polyacetal. Consequently, a stick-slip phenomenon occurs between objects such as switch members of OA equipment and car audio system members fitted to each other, due to vibrations of the equipment or vibrations of automobiles during starting and driving, producing a squeaking sound.
The friction coefficient (dynamic friction coefficient, amplitude of dynamic friction coefficient) of rubber-reinforced thermoplastic resin compositions is conventionally reduced by the addition of lubricants such as polytetrafluoroethylene, silicones and polyethylene. For example, it has been proposed that rubber-reinforced thermoplastic resin compositions be mixed with lubricants such as silicones (Patent Literature 1), silicones having a specific viscosity (Patent Literature 2), and polytetrafluoroethylene or polyethylene (Patent Literature 3).
This approach involving the addition of these lubricants increases the lubricating properties of shaped articles by allowing the lubricants blended in the rubber-reinforced thermoplastic resin compositions to bleed out on the surface of shaped articles, thereby reducing the friction coefficient. As a result of this, the lubricants that have bled out deteriorate the surface appearance of shaped articles. Further, the lubricating properties are decreased with time due to the gradual loss of the lubricants that have bled out.